Continuous spinal anesthesia procedures and continuous epidural anesthesia procedures are of course well known in the art. In either case, the distal end of the catheter is first introduced in to the patient's body with the proximal or trailing end outside the body to receive the anesthetic.
To do so, an adapter is employed connecting the proximal end of the catheter at one end of the adapter to a source of liquid anesthetic, e.g. a syringe, at the other. The adapter has a channel communicating with the catheter end so that when the liquid anesthetic is introduced into the channel, it passes through the catheter into either the subarachnoid space, if the spinal anesthesia procedure is used or into the epidural space, as would be the case with the epidural anesthesia procedure.
As an illustration of prior adapters for this purpose, mention may be made of those described and claimed in U.S. Pat. No. 4,187,848 issued to Glenn N. Taylor. As disclosed therein, the adapter comprises two separate members, one being designated as the body member, the other being termed a compression member. The body member has an elongated bore and an opening at its distal end for receiving the proximal end of the catheter extending from the patient's body. An elongated elastic plug having a channel extending therethrough is seated in uncompressed condition within the bore of the body member, the channel being aligned with the opening of the body member so that the catheter end inserted in the opening can be positioned within the plug channel. The compression member has a port at its proximal end where the tip of a syringe may be releasably engaged for injecting liquid anesthetic. A passageway for fluid extends between the two ends of the compression member so that when the proximal end of the body member and the distal end of the compression member are secured together, the liquid anesthetic injected from the syringe may be pumped into the catheter. To connect the two members, the proximal end of the body member is provided with external threads and the distal end of the compression member with internal threads mating with the body member threads. When the threads are tightened to secure the two members, the plug is compressed to retain the catheter end positioned therein.
While a catheter adapter of this general description is in theory entirely satisfactory for connecting the catheter to the syringe, the prior art two-piece adapters currently in use, as exemplified by the teachings of the aforementioned patent, do nevertheless suffer from certain inherent disadvantages.
A primary disadvantage is that there is no locking engagement to maintain the two components together, as intended. Consequently, there is a danger for unscrewing or back-off, resulting in loss of compressive force on the plug and, consequently, in separation of the catheter from the adapter.
Another problem which occurs from time-to-time is the human error in attempting to screw the two components together. It sometimes happens that one of the components is dropped. This human error necessitates the time and expense of opening a whole new sterile tray to replace the dropped component.
It is accordingly the task of this invention to provide an improved adapter which will obviate the aforementioned problems.